Assemble a cohort of approximately 20,000 civilians employed at Hill Air Force Base, Utah, during 1952. Compare the mortality experience of exposed workers at Hill Air Force Base with internal and external control groups. For causes ofdeath found in excess, determine associations with particular jobs or exposures. Determine, by using cost-effective sequential procedures, the present day vital status of study subjects, including last known or current address if living, using such resources as Office of Personnel Management records, current Union rosters, Social Security Administration files, State Motor Vehicle Bureaus, State Vital Record Departments, telephone directories, credit bureaus, and others as needed. Obtain copies of official death certificates from State Vital Record departments for those subjects reported as deceased, and transfer these copies to NIH for cause of death coding. Develop manual and computer systems to effeciently record and maintain the data.